Thermodynamics of Impurity Doping Reactions in Vapor Growth of Ge

The incorporation of impurities into single crystal layers of Ge grown by the disproportionation reaction 2GeI 2 \rightleftarrowsGe+GeI 4 , is studied thermodynamically. Impurity iodides formed in the source region are carried over substrate wafers where impurity atoms are liberated mainly through the reduction by Ge or GeI 2 . The amount of impurity incorporated depends largely upon the yields of reactions involved in the doping process, and the analysis leads to the conclusion that Sb, P and As are favorable as donor impurities while Ga, In and BI 3 as acceptor impurities.